Myth 2: 'Straight' sex is safe: Heterosexual sex is safe

 

THERE IS now abundant scientific proof that HIV can spread between the sexes during vaginal intercourse. Scientists also have evidence for 'second-generation' transmission from one heterosexual to another and then a third.

Studies of hundreds of stable heterosexual couples have found that over a period of several years there is about a 20 per cent risk of infected men passing the virus to their female partners.

The risk of woman-to-man transmission is about half that.

Detailed questionnaires of the sexual activities of the couples revealed that anal sex and sex during menstruation were not essential for transmission of HIV.

In one study of 563 European couples, '40 out of 82 infected women never practised anal sex and 8 out of 19 infected men never had intercourse during their partners' menses'.

Scientists have used such data to assess the infectiousness of HIV. They conclude that an uninfected woman has about a 1 in 1,000 risk of catching the virus from having sex once with an infected man - the risk is about half for transmission from women to men.

Although this shows that HIV is not as infectious as many other sexually transmitted diseases, it does not offer grounds for complacency. The dangerous and often overlooked aspect of HIV is that infected people remain infectious for many years before showing the first signs of Aids.

Professor Roy Anderson, of Imperial College in London, who constructs mathematical models of how HIV is likely to spread in years to come, says that a risk of 1 in 1,000 per sex act may not appear worrying.

But what is worrying is that infected heterosexuals can typically have sex twice a week for 10 years without knowing they are HIV-positive. This means the epidemic of Aids, unlike past scourges such as bubonic plague and syphilis, is moving over a period of decades rather than weeks or months.

The ease with which HIV can pass from one couple to another is illustrated by the case of a woman in her twenties, who had passed HIV to her boyfriend. Later in the same year, after that relationship had ended, he passed the virus to his new partner, another woman in her twenties. None of the three had injected drugs.

Scientists who have studied this and other cases of 'second-generation' transmission within the UK suspect that, after a person becomes initially infected, he or she becomes relatively infectious for a period of several weeks as the virus multiplies rapidly within their blood system - what doctors describe as initial 'viraemia'.

A longer period of dormancy, lasting several years, follows. This is apparently matched by a lower level of infectiousness, they suspect. Towards the end of the dormant period, when the virus begins to multiply again prior to the onset of Aids, HIV-positive patients appear to become more infectious again.

Anne Johnson, senior lecturer in epidemiology at University College and Middlesex School of Medicine in London, said that most new HIV infections in heterosexuals were now due to the second-generation spread of HIV and a significant minority - about 10 per cent - were the result of transmission entirely within the UK. This category, she said, showed a 'consistent annual increase'.

Scientists at the Government's Communicable Disease Surveillance Centre in London said that 'anal sex between heterosexuals has contributd very little, if any, to the observed second-generation heterosexual transmission' of HIV.

First-generation transmission - for example from a drug user or bisexual to heterosexual - is still happening in Britain, in spite of couples being aware that one of them is HIV- positive.

Roy Robertson, an Edinburgh GP, who has been following nearly 200 couples where one partner is an HIV- positive drug user, said that he was still seeing uninfected partners becoming HIV-positive.

He saw about six cases a year, he said. One of the youngest was a 17- year-old girl whose boyfriend injected drugs many years ago.

'Many are in long-term relationships where they often do not use condoms and when they see that they are still uninfected, they say the doctors are wrong. Then, when eventually they do get the virus, they are absolutely devastated,' he said.

'They recognise that the whole thing is a mess because the information they are getting from newspapers about the risk of heterosexual Aids is not what their doctors are telling them. As a result, our street cred is pretty low.'

Start your day with The Independent, sign up for daily news emails
Have you tried new the Independent Digital Edition apps?
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Home Care / Support Workers

£7 - £10 per hour: Recruitment Genius: This care provider is looking for Home ...

Recruitment Genius: Web Team Leader

£30000 - £35000 per annum: Recruitment Genius: One of the UK's leading web des...

Recruitment Genius: Client Manager

£27000 - £35000 per annum: Recruitment Genius: A growing, successful, friendly...

Recruitment Genius: Property Negotiator - OTE £20,000+

£16000 - £25000 per annum: Recruitment Genius: This family owned, independent ...

Day In a Page

Greece says 'No': A night of huge celebrations in Athens as voters decisively back Tsipras and his anti-austerity stance in historic referendum

Greece referendum

Greeks say 'No' to austerity and plunge Europe into crisis
Ten years after the 7/7 terror attacks, is Britain an altered state?

7/7 bombings anniversary

Ten years after the terror attacks, is Britain an altered state?
Beautiful evening dresses are some of the loveliest Donatella has created

Versace haute couture review

Beautiful evening dresses are some of the loveliest Donatella has ever created
No hope and no jobs, so Gaza's young risk their lives, climb the fence and run for it

No hope and no jobs in Gaza

So the young risk their lives and run for it
Fashion apps: Retailers roll together shopping and social networking for mobile customers

Fashion apps

Retailers roll together shopping and social networking for mobile customers
The Greek referendum exposes a gaping hole at the heart of the European Union – its distinct lack of any genuine popular legitimacy

Gaping hole at the heart of the European Union

Treatment of Greece has shown up a lack of genuine legitimacy
Number of young homeless in Britain 'more than three times the official figures'

'Everything changed when I went to the hostel'

Number of young homeless people in Britain is 'more than three times the official figures'
Compton Cricket Club

Compton Cricket Club

Portraits of LA cricketers from notorious suburb to be displayed in London
London now the global money-laundering centre for the drug trade, says crime expert

Wlecome to London, drug money-laundering centre for the world

'Mexico is its heart and London is its head'
The Buddhist temple minutes from Centre Court that helps a winner keep on winning

The Buddhist temple minutes from Centre Court

It helps a winner keep on winning
Is this the future of flying: battery-powered planes made of plastic, and without flight decks?

Is this the future of flying?

Battery-powered planes made of plastic, and without flight decks
Isis are barbarians – but the Caliphate is a dream at the heart of all Muslim traditions

Isis are barbarians

but the Caliphate is an ancient Muslim ideal
The Brink's-Mat curse strikes again: three tons of stolen gold that brought only grief

Curse of Brink's Mat strikes again

Death of John 'Goldfinger' Palmer the latest killing related to 1983 heist
Greece debt crisis: 'The ministers talk to us about miracles' – why Greeks are cynical ahead of the bailout referendum

'The ministers talk to us about miracles'

Why Greeks are cynical ahead of the bailout referendum
Call of the wild: How science is learning to decode the way animals communicate

Call of the wild

How science is learning to decode the way animals communicate